I thought the "new cool way" to do plumbing for human consumption was to use copper piping... I wonder if it's lined with something? Anyway, I think "copper is bad for you/octo" is an overgeneralization-- some chemical compounds/contexts involving copper are clearly bad for cephs as people here know from experience, but unless I'm remember wrong, cephalopod blood uses hematocyanin as its blood oxygen transporter, analogous to hemoglobin in mammals, and where hemoglobin has iron, hematocyanin has copper, so in fact octopi can't live without copper.
I assume that copper ions or copper chloride or something in the water, however, has some seriously bad effects. Certainly, human beings can't function without chlorine and Nitric Oxide, but inhaling either of them in a pure form is extremely lethal.
I wonder what the mechanism/chemistry is for copper in the water being bad for invertebrates...
I also hadn't heard of copper in water being particularly bad for people, so I'm a bit surprised to hear that note. Of course, any stuff in the water will be dependent on the concentration; my impression is that small concentrations of copper are a lot worse for cephalopods than most other animals (like us).
It's hard to keep in perspective that "small quantities" can range from grams-per-litre to parts-per-million to parts-per-billion, and for different things, the dangerous amount may be in any of those ranges, even if they all seem like "very small quantities" on the scales we're used to dealing with.